This program of research concerns the chemistry of foodborne environmental toxicants; characterization of their toxicity, carcinogenicity and mutagenicity in several bioassay systems; and experiments related to interactions with cell macromolecules critical to carcinogenicity and mutagenicity. The program comprises four segments utilizing chemical, cellular, intact animal and subcellular experimental models. Projects within these segments deal with: (1) synthesis, detection, and activation of N-nitroso compounds, and with products formed as a result of interactions between proteins, amino acids or nucleic acids with lipid peroxides; (2) mutagenic transformation of human lymphoblasts in culture, and DNA damage and repair in bacterial or eucaryotic cells; (3) fetal and neonatal responses to food additives and contaminants, interactions among environmental chemicals in producing cancer, and carcinogenesis assay of nitrosation products and other compounds; and (4) carcinogen effects on non-histone nuclear proteins, interactions with steroid receptors and other cellular proteins, and alterations in nucleic acid structure.